The present invention relates to a mobile terminal device having a route guiding function and a route guiding method utilizing the mobile terminal device.
Up to now, the mobile phone with a map navigation function, to which a GPS function of sensing a current position and a bearing compass function using a geomagnetic bearing sensor are provided, etc., and have been manufactured as a product.
For example, the navigation system utilizing the mobile terminal device such as the mobile phone is disclosed in JP H10-197277-A. According to this reference, the user's terminal acquires positional information of the present location by using the GPS. The user's terminal then sets positional information of the destination by using a function of the service server. Next, the device searches a guide route via the service server, while the service server, while the service server offers sequentially positional information of transit points in the middle of the guide route to the destination every time the user arrives at each transit point until the user comes up to the destination. The user's terminal derives a guiding direction indicating the direction of the halfway targets required until the user arrives at the destination. The user's detects the direction in which the LCD of the terminal is directed from the positional information received from the service server. The terminal obtains a relative guiding direction indicating the direction of the destination with respect to the direction of the LCD, and informs the user of the relative guiding direction with an arrow or a sound. The configuration set forth in JP H10-197277-A is able to guide the direction to the destination without map information that needs a large information contents.
Incidentally, since normally the top portion of the displayed map points the North bearing, the user must appreciate previously that the upper side of the displayed map is directed to the North bearing to find the user's destination. As the case may be, the user must find where the land mark indicated on the map is actually located. Further, the user must appreciate at which place the user's own current position is located on the map and in which direction the position of the destination on the map is placed relatively from the user's own current bearing (the current direction of the mobile terminal device). For the above reasons, in order to arrive at the position of the destination from the user's own current position, it took the user a lot of time to decide which way the user should start walking along.
Further, in the map navigation function, in case such a mode is taken that the map information is downloaded from the server, first a wide area map must be downloaded in the prior art. Second, the area of the map must be reduced several times by using the zoom-in function to get a map range containing the destination and the user's own current position. Otherwise, map information with different map scales must be downloaded several times, and thus it is very troublesome to execute such function.
In the technology set forth in JP H10-197277-A, the system is downsized according to the above configuration, nevertheless the user acquires the positional information of the next destination via the communication with the service server every arrival of the halfway destination on the guide route until the user reaches to the final destination without the map. Therefore, the user must communicate with the service server until the user reaches to the final destination. As a result, in case of a communication trouble, the guidance to indicate the next destination is not properly issued, so that in some cases the user may fail to reach the final destination. Further, in case the proper guide route is not derived and thus the guiding direction is given in disregard of the presence of the actually existing building, etc., it may happen that the user cannot know in which way he or she should actually go, e.g., the situation that the user cannot go in that direction because of the building, etc. located in the guiding direction.